(N-Substituted-pyridyl)-alkyl sulfonic acid betaines as electroplating additives

ABSTRACT

Novel pyridyl alkyl sulfonic acid betaines useful as additives to nickel electroplating baths.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 763,452, filed Jan. 27, 1977,now issued as U.S. Pat. No. 4,067,785, which in turn is a continuationin part of Ser. No. 666,525, filed Mar. 12, 1976 and now abandoned.

BACKGROUND OF THE INVENTION

Pyridyl sulfonic acids or pyridyl alkyl sulfonic acids as additives tonickel plating baths have been reported. In U.S. Pat. No. 2,839,456,4-pyridyl ethane sulfonic acid, in combination with other additives, isdescribed as a brightener. Though 2- and 4-pyridine ethane sulfonicacids do improve the luster of deposited nickel layers, they have noinfluence on their leveling. In U.S. Pat. No. 3,444,056, certainquaternary compounds of pyridine-3-sulfonic acid are mentioned aslevelers and brighteners. The N-methyl-pyridine-3-sulfonic acid betaineand N-allyl-pyridine-3-sulfonic acid betaine mentioned in this patentare, however, not fully satisfactory. It appears that nickel depositsturn lusterless and brittle with a too low ampere hour load per liter ofnickel bath. This behavior of the bath cannot be prevented by any of theregeneration methods employed in electroplating. The instant compoundsof this invention are agents which produce a highly leveled nickeldeposit of excellent ductility in a far more constant bath.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention relates to a novel class of pyridyl alkyl sulfonic acidbetaines represented by the following formula: ##STR1## in which thesubstituent --(CH₂)_(n) SO₃.sup.⊖ is in the 2- or 4-position of thepyridyl ring; n is the integer 1 or 2; and R is a member selected fromthe group consisting of methyl; methallyl; CH₂ COOH; CH₂ (CH₂)_(x) CH₂SO₃ Na wherein x is the integer 1 or 2; sodium 2-hydroxypropylsulfonate;sodium 2-hydroxybutylsulfonate; sodium 3-hydroxybutylsulfonate; benzyl;halobenzyl; loweralkylbenzyl; and benzyl substituted with the group:##STR2## wherein the substituent --(CH₂)_(n) SO₃.sup.⊖ is in the 2- or4-position of the pyridyl ring and n is the integer 1 or 2.

For purposes of nomenclature, the aforementioned groups: sodium2-hydroxypropylsulfonate; sodium 2-hydroxybutylsulfonate and sodium3-hydroxybutylsulfonate may also be denoted as3-Na-sulfo-2-hydroxypropyl, 4-Na-sulfo-2-hydroxybutyl and4-Na-sulfo-3-hydroxybutyl, respectively. Similarly, the aforementionedgroup: CH₂ (CH₂)_(x) CH₂ SO₃ Na may be denoted as 3-Na-sulfopropyl whenx = 1, and 4-Na-sulfobutyl when x = 2.

As used herein, the term "loweralkyl" refers to an aliphatic hydrocarbonwith 1 to 4 carbons; and the term "halo" includes bromo and fluoro, withchloro preferred, that is, those halogens with atomic weight less than80.

The subject pyridyl alkyl sulfonic acid betaines (I) are convenientlyprepared by quaternization of an appropriate 2- or 4-pyridyl alkylsulfonic acid (II-a) or its alkali metal alt, preferably the sodium salt(II-b): ##STR3## wherein the substituent --(CH₂)_(n) SO₃ (H,Na) is inthe 2- or 4-position of the pyridyl ring and n is 1 or 2. Quaternizationis accomplished by using an appropriate quaternizing agent suitable forintroducing the aforementioned R-substituent on the ring nitrogen of thepyridyl function, such as, for example, dimethyl sulfate, methallylchloride, sodium chloroacetate, propansultone, butansultone, anappropriate benzyl halide, an appropropriately substitutedhaloloweralkyl, and the like agents, as more fully described andexemplified hereinafter. The compounds of formulas (II-a) and (II-b) areobtained from known procedures in the art, for example, by reactionbetween 2- or 4-vinylpyridine and sodium bisulfite according to J. Am.Chem. Soc., 69, 2465 (1947) for the preparation of the ethyl sulfonicacids or by reaction between appropriate haloalkyl pyridines and sodiumsulfite.

To prepare the formula (I) compounds with R equal to methyl, theprecursor (II-a) or (II-b) is reacted with dimethyl sulfate as thequaternizing agent, generally utilizing a slight stoichiometric excessof the latter. Elevated temperatures may be employed to enhance the rateof reaction. Since dimethyl sulfate is a liquid at ambient temperatures,the use of an additional organic solvent for the quaternization reactionis normally unnecessary. The reaction may be illustrated as follows:##STR4##

To prepare the formula (I) compounds with R equal to CH₂ COOH,approximately equimolar amounts of the precursor (II-b) and haloaceticacid in the form of an alkali metal salt, for example, sodium (III) inan aqueous solvent are reacted, preferably under reflux conditions. Thereaction mixture containing the thus-formed alkali metal salt is thencooled and treated with a suitable mineral acid, e.g., hydrochloricacid, to convert the salt (IV) to its corresponding acid form (V). Theforegoing reaction may be illustrated as follows: ##STR5##

The compounds of formula (I) wherein R is benzyl, halobenzyl orloweralkylbenzyl are prepared in similar fashion. The precursor (II-b)is reacted with an appropriate benzyl halide (VI), e.g., benzylchloride, halobenzyl chloride or loweralkylbenzyl chloride, in water,preferably under reflux conditions. After cooling and treatment withmineral acid, the desired N-benzyl substituted product (VII) isobtained. ##STR6##

The compounds of formula (I) wherein R is methylallyl may be similarlyquaternized, as described above for R equal to a benzyl function, exceptthat methallyl chloride is used as the quaternizing agent.

The compounds of formula (I) wherein R is CH₂ (CH₂)_(x) SO₃ Na may beprepared by quaternization of the precursor (II-b) with propansultone orbutansultone, respectively (VIII), in an aqueous solvent. Elevatedtemperatures may be employed to enhance the rate of reaction. Treatmentof the reaction mixture with mineral acid, preferably after volumeconcentration, is employed to counteract the sodium ion content followedby conventional treatment with suitable bases yielding sodium anion,e.g., sodium methylate in methanol to yield the desired sodiumalkylsulfonate derivative (IX). In like manner, the compounds of formula(I) wherein R is sodium 2-hydroxypropylsulfonate, sodium2-hydroxybutylsulfonate or sodium 3-hydroxybutylsulfonate are obtainedby quaternizing (II-b) with an appropriate halo-hydroxyalkyl sulfonicacid in sodium salt form, as illustrated below by sodium2-hydroxypropylsulfonate (X). ##STR7##

To prepare the compounds of formula (I) wherein R is benzyl substitutedwith the group: ##STR8## α,α'-dichloroxylol (o-, m- or p-form) isreacted with at least two stoichiometric equivalents of the precursor(II-b) in an aqueous solvent. Elevated temperatures are advantageouslyemployed to enhance the rate of reaction. Upon completion of thereaction and subsequent cooling of the reaction mixture, followed bytreatment with mineral acid, the desired products are obtained throughconventional recovery techniques. The foregoing quaternization can beillustrated with α,α'-dichloro-p-xylol as follows: ##STR9##

The subject compounds of formula (I) produce a highly leveled nickeldeposit of excellent ductility when used as additives for theelectro-deposition of nickel coatings in conventional galvanic nickelbaths. These compounds are suitable for use in galvanic nickel bathseither alone or in combination with other luster-promoting or levelingadditives. For example, an optinum luster is obtained in combinationwith such generally known brighteners as saccharin, diarylsulfonimides,naphthalene trisulfonic acids or sulfonates, acetylenic compounds suchas, for example, propargyl alcohol, and the like. The latter isespecially useful in enhancing the leveling effect of the subjectcompounds. Furthermore, the subject compounds may be used in conjunctionwith conventional wetting agents such as, for example, sodium laurylsulfate or with other ionized or non-ionized agents that decreasesurface tension. The galvanic baths may also contain conventionalbuffering agents, such as, for example, boric acid, tartrates, etc.

The galvanic bath comprises an acidic solution of a nickel saltgenerally one selected from the group consisting of nickel sulfate,nickel sulfamate, nickel fluoborate, nickel chloride, nickel acetate andthe like. Mixtures of such salts are also suitable. Typical of thenickel galvanic baths in which the subject compounds (I) may be employedare those shown in U.S. Pat. No. 3,444,056. The subject compounds may beadvantageously used in concentrations ranging from about 0.05 gram perliter (g/l) to about 2.0 g/l of bath, although from about 0.1 to about0.5 g/l is preferred. Other preferred parameters are a bath temperatureof about 50°-60° C., a pH of about 3.5-5.0 with about 4.5 mostpreferred, and a current density ranging from about 1 to about 10amp/dm². The bath may be mechanically or air stirred. If the latter, theuse of a non-foamy wetting agent is recommended.

In view of the foregoing, the present invention provides an improvementin galvanic baths for electro-depositing leveled and lustrous nickelcomprising an aqueous acidic solution of at least one nickel salt. Theimprovement in such baths comprises a pyridyl alkyl sulfonic acidbetaine of formula (I) in a concentration of about 0.05-2.0 grams perliter and, preferably, about 0.1-0.5 grams per liter. The preferredadditives of formula (i) are those wherein R is either benzyl or benzylsubstituted with the previously described group: ##STR10## including butnot limited to 2-[N-benzylpyridyl-(2)]-ethane sulfonic acid betaine and1,2-bis-[2-(2-sulfoethyl)-pyridinium-(1)-methyl]-benzene.

The following examples are intended to illustrate, but not to limit, thescope of the present invention.

EXAMPLE I ##STR11##

A. 2-[N-carboxymethyl-pyridyl-(2)]-ethanesulfonic acid bentaine:

23.3 Grams (0.2 mol) of chloroacetic acid sodium salt, 41.8 g (0.2 mol)of 2-pyridyl ethane sulfonic acid sodium salt and 50 g of water arerefluxed for five hours. Following cooling down to 20° C., the reactionmixture is treated with 250 g of concentrated hydrochloric acid. Thecrystallized sodium chloride is filtered off by suction and the solutionis concentrated to dryness under vacuum. The residue is mixed with 350ml of methanol. The product, 27.5 g of2-[N-carboxymethyl-pyridyl-(2)]-ethanesulfonic acid betaine, whichcrystallizes at room temperature is filtered off by suction and vacuumdried at 110° C.; decomposition point: 214° C.

B. 2-[N-carboxymethyl-pyridyl-(4)]-ethane sulfonic acid betaine isobtained in the same way, by employing an equivalent quantity each of4-pyridyl ethane sulfonic acid sodium salt and chloroacetic acid sodiumsalt as reactants; decomposition point: 234° C.

C. [N-carboxymethyl-pyridyl-(4)]-methanesulfonic acid betaine isobtained in the same way, by employing an equivalent quantity each of4-pyridyl methane sulfonic acid sodium salt and chloroacetic acid sodiumsalt as reactants; decomposition point: 290° C.

EXAMPLE II ##STR12##

A. 2[N-methyl-pyridyl-(2)]-ethane sulfonic acid betaine:

55 Grams (0.29 mol) of 2-pyridyl ethane sulfonic acid and 40.7 g (0.32mol) of dimethyl sulfate are heated to 150°-155° C. Two hours later thereaction mixture is allowed to cool down to 20° C. and a mixture of 40ml of ethanol and 40 ml of isopropanol are added. After standing for 24hours, the precipitated crude product is filtered off by suction. Afterdouble recrystallization from methanol, the white crystals are vacuumdried at 80° C. The final yield is 16.8 g of2-[N-methyl-pyridyl-(2)]-ethane sulfonic acid betaine; decompositionpoint: 209° C.

B. 2-[N-methyl-pyridyl-(4)]-ethane sulfonic acid betaine is prepared inthe same manner from equivalent amounts of 4-pyridyl ethane sulfonicacid and dimethyl sulfate.

EXAMPLE III ##STR13##

A. 2-[N-(2-methylbenzyl)-pyridyl-(2)]-ethane sulfonic acid betaine:

41.8 Grams (0.2 mol) of 2-pyridyl ethane sulfonic acid sodium salt, 28.1g (0.2 mol) of o-methylbenzyl chloride and 20 g of water are refluxedfor 5 hours. The reaction mixture is then allowed to cool down to 20° C.and 250 g of concentrated hydrochloric acid are added. The precipitatedsodium chloride is filtered off by suction and the filtrate concentratedto dryness under vacuum. The residue is mixed with 200 ml of ethanol andthe precipitated white crystal mass is filtered off by suction andvacuum dried at 110° C. to yield 32 g of2-[N-(2-methylbenzyl)-pyridyl-(2)]-ethane sulfonic acid betaine;decomposition point: 223° C.

B. 2-[N-(2-methylbenzyl)-pyridyl-(4)]-ethane sulfonic acid betaine isobtained in the same way, by using an equivalent quantity each of4-pyridyl ethane sulfonic acid sodium salt and o-methylbenzylchloride asreactants; decomposition point: 241° C.

EXAMPLE IV ##STR14##

[N-benzyl-pyridyl-(2)]methane sulfonic acid betaine:

17.3 Grams (0.1 mol) of 2-pyridyl methansulfonic acid sodium salt, 12.7g (0.1 mol) of benzylchloride and 13 g of water are refluxed for 2 hoursat 100°-105° C. The reaction mixture is allowed to cool down to 20° C.and 100 ml of concentrated hydrochloric acid are added. The precipitatedsodium chloride is filtered off and the solution concentrated todryness. The residue is mixed with 100 ml of ethanol. The precipitatedwhite crystals are filtered off and vacuum dried at 110° C. to yield13.7 g of [N-benzyl-pyridyl-(2)]methane sulfonic acid betaine;decomposition point: 230° C.

EXAMPLE V

By following the procedures of Examples III and IV, accept thatequivalent quantities of appropriate reactants are employed, thefollowing respective products are obtained:

2-[N-benzylpyridyl-(2)]-ethane sulfonic acid betaine; decompositionpoint: 198° C.

2-[n-benzylpyridyl-(4)]-ethane sulfonic acid betaine; decompositionpoint: 234° C.

2-[n-(2-chlorobenzyl)-pyridyl-(2)]-ethane sulfonic acid betaine;decomposition point: 238° C.

2-[n-(4-chlorobenzyl)-pyridyl-(2)]-ethane sulfonic acid betaine;decomposition point: 201° C.

2-[n-(2-chlorobenzyl)-pyridyl-(4)]-ethane sulfonic acid betaine;decomposition point: 237° C.

EXAMPLE VI ##STR15##

A. 2-[N-(3-Na-sulfopropyl)-pyridyl-(2)]-ethane sulfonic acid betaine:

41.8 Grams (0.2 mol) of 2-pyridyl ethane sulfonic acid sodium salt, 30.5g (0.25 mol) of propansultone, 200 g of methanol and 15 g of water areheated to 65° C. for 7 hours. The reaction mixture is then concentratedunder vacuum and the residue is mixed with 200 ml of concentratedhydrochloric acid. The precipitated sodium chloride is filtered off andthe mother liquor concentrated to dryness. The oily residue is dissolvedin 200 ml of methanol and allowed to stand for 2 days. Some 2-pyridylethane sulfonic acid, which precipitates within this time, is filteredoff and the filtrate is neutralized with 30% sodium methylate solution(in methanol). A white salt precipitates which is filtered off andvacuum dried at 110° C. to yield 17 g of2-[N-(3-Na-sulfopropyl)-pyridyl-(2)]-ethane sulfonic acid betaine;decomposition point: 228° C.

B. The procedure of Example VI-A is repeated except that an equivalentamount of butansultone is substituted for the propansultone used thereinto yield the corresponding product,2-[N-(4-Na-sulfobutyl)-pyridyl-(2)]-ethane sulfonic acid betaine.

C. By following the procedure of Example VI-A, except that equivalentamounts of appropriate starting materials are employed as reactants,there are obtained as respective products:

[N-(3-Na-sulfopropyl)-pyridyl-(4)]-methane sulfonic acid betaine; and

2-[N-(4-Na-sulfobutyl)-pyridyl-(4)]-ethane sulfonic acid betaine.

EXAMPLE VII ##STR16##

A. 2-[N-(3-Na-sulfo-2-hydroxypropyl)-pyridyl-(2)]-ethane sulfonic acidbetaine:

20.9 Grams (0.1 mol) of 2-pyridyl ethane sulfonic acid sodium salt, 19.7g (0.1 mol) of 3-chloro-2-hydroxypropyl sulfonic acid-(1)-sodium saltand 20 ml of water are heated at 95° C. for 6 hours. The reactionmixture is then concentrated under vacuum and the residue is mixed with100 ml of concentrated hydrochloric acid. The insoluble sodium chlorideis filtered off and the mother liquor concentrated to dryness. The oilyresidue is dissolved in 100 ml of methanol and allowed to stand for 2days. Some 2-pyridyl ethane sulfonic acid, which precipitates withinthis time, is filtered off and the filtrate is neutralized with 30%sodium methylate solution (in methanol). The precipitated white salt isfiltered off and vacuum dried at 110° C. to yield 11 g of2-[n-(3-Na-sulfo-2-hydroxypropyl)-pyridyl-(2)]-ethane sulfonic acidbetaine; decomposition point: 183° C.

B. The procedure of Example VII-A is followed, except that equivalentamounts of appropriate starting materials are employed as reactants, toyield the following respective products:

2-[N-(4-Na-sulfo-2-hydroxybutyl)-pyridyl-(2)]-ethane sulfonic acidbetaine;

2-[N-(4-Na-sulfo-3-hydroxybutyl)-pyridyl-(4)]-ethane sulfonic acidbetaine; and

[N-(3-Na-sulfo-2-hydroxypropyl)-pyridyl-(4)]-methane sulfonic acidbetaine.

EXAMPLE VIII ##STR17##

A. 1,4-Bis-[2-(2-sulfoethyl)-pyridinium-(1)-methyl]-benzene:

62.8 Grams (0.3 mol) of 2-pyridyl ethane sulfonic acid sodium salt, 17.5g (0.1 mol) of α,α'-dichloro-p-xylol and 50 g of water are heated to100°-105° C. for 4 hours. The reaction mixture is then cooled and 200 gof concentrated hydrochloric acid are added. The precipitated sodiumchloride is filtered off and, the filtrate concentrated under vacuum todryness. 200 ml of methanol are added to the residue. The precipitatedimpure crystals are filtered off, dissolved in 120 ml of water at 20°C., and again precipitated by adding 480 ml of ethanol. The whitecrystal mass is filtered off and vacuum dried at 110° C. to yield 26 gof 1,4-bis-[2-(2-sulfoethyl)-pyridinium-(1)-methyl]-benzene;decomposition point: > 350° C.

B. In the same manner, except that equivalent amounts of appropriatereactants are employed, there are obtained as respective products:

1,2-bis-[2-(2-sulfoethyl)-pyridinium-(1)-methyl]-benzene; decompositionpoint: 248° C.

1,3-bis-[2-(2-sulfoethyl)-pyridinium-(1)-methyl]-benzene; decompositionpoint: 251° C.

1,4-bis-[4-(2-sulfoethyl)-pyridinium-(1)-methyl]-benzene; decompositionpoint: 258° C.

EXAMPLE IX

The following illustrate typical galvanic nickel baths in which thesubject compounds of formula (I) may be employed. It is understood thatthe hereinmentioned subject compounds are not listed for the purpose oflimiting the scope of the invention thereto but to exemplify theusefulness of all compounds within formula (I).

    ______________________________________                                                      A                                                               ______________________________________                                        Nickel sulfate . 7H.sub.2 O                                                                           g/l      310                                          Nickel chloride . 6H.sub.2 O                                                                          g/l      50                                           Boric Acid              g/l      40                                           Lauryl sulfate          g/l      0.2                                          Saccharin               g/l      2.0                                          2-[N-benzylpyridyl-(2)]-ethanesulfonic                                        acid betaine            g/l      0.3                                          pH                               4.6                                          Temperature             ° C                                                                             50-60                                        Current density         amp/dm.sup.2                                                                           1-7                                          ______________________________________                                    

    ______________________________________                                                      B                                                               ______________________________________                                        Nickel sulfate . 7H.sub.2 O                                                                           g/l      310                                          Nickel chloride . 6H.sub.2 O                                                                          g/l      50                                           Boric Acid              g/l      40                                           Lauryl sulfate          g/l      0.2                                          Saccharin sodium        g/l      1.0                                          1,3,6-naphthalene trisulfonic acid sodium                                     salt                    g/l      1.0                                          2-[N-benzylpyridyl-(4)]-ethanesulfonic                                        acid betaine            g/l      0.3                                          pH                               4.6                                          Temperature             ° C                                                                             50-60                                        Current density         amp/dm.sup.2                                                                           1-7                                          ______________________________________                                    

    ______________________________________                                                      C                                                               ______________________________________                                        Nickel sulfate . 7H.sub.2 O                                                                           g/l      280                                          Nickel chloride . 6H.sub.2 O                                                                          g/l      40                                           Boric Acid              g/l      40                                           Lauryl sulfate          g/l      0.2                                          Dibenzylsulfonimide     g/l      8.0                                          Propargyl alcohol       g/l      0.04                                         1,2-bis[2-(2-sulfoethyl)-pyridinium(1)-                                       methyl]-benzene         g/l      0.15                                         pH                               4.6                                          Temperature             ° C                                                                             50-60                                        Current density         amp/dm.sup.2                                                                           1-7                                          ______________________________________                                    

EXAMPLE X

A. The procedure of Example III-A is followed except that 18 g (0.2mole) of methallyl chloride is substituted for the o-methylbenzylchloride used therein to yield, as the final product,2-[N-(2-methylpropen-2-yl)-pyridyl-(2)]-ethane sulfonic acid betaine,also known as 2-[N-methallyl-pyridyl-(2)]-ethane sulfonic acid betaine,decomposition point: 196° C.

B. 2-[N(2-methylpropen-2-yl)-pyridyl-(4)]-ethane sulfonic acid betaine,also known as 2-[N-methallyl-pyridyl-(4)]-ethane sulfonic acid betaine,decomposition point: 208° C., is obtained in similar fashion by using anequivalent quantity each of 4-pyridyl ethane sulfonic acid sodium saltand methallyl chloride as reactants.

What is claimed is:
 1. A pyridyl alkyl sulfonic acid betaine having theformula: ##STR18## in which the substituent --(CH₂)_(n) SO₃.sup.⊖ is inthe 2- or 4-position of the pyridyl ring; n is the integer 1 or 2; and Ris a member selected from the group consisting of methyl; methallyl;benzyl; halobenzyl wherein said halo has an atomic weight less than 80;loweralkylbenzyl wherein said loweralkyl has from 1 to 4 carbons; andbenzyl substituted with the group: ##STR19## wherein the substituent--(CH₂)_(n) SO₃.sup.⊖ is in the 2- or 4-position of the pyridyl ring andn is the integer 1 or
 2. 2. 2-[N-methyl-pyridyl-(2)]-ethanesulfonic acidbetaine.
 3. 2-[N-(2-methylbenzyl)-pyridyl-(2)]-ethanesulfonic acidbetaine.
 4. 2-[N-(2-methylbenzyl)-pyridyl-(4)]-ethanesulfonic acidbetaine.
 5. [N-benzylpyridyl-(2)]methanesulfonic acid betaine. 6.2-[N-benzylpyridyl-(2)]-ethanesulfonic acid betaine. 7.2-[N-benzylpyridyl-(4)]-ethanesulfonic acid betaine. 8.2-[N-(2-chlorobenzyl)-pyridyl-(2)]-ethanesulfonic acid betaine. 9.2-[N-(4-chlorobenzyl)-pyridyl-(2)]-ethanesulfonic acid betaine. 10.2-[N-(2-chlorobenzyl)-pyridyl-(4)]-ethanesulfonic acid betaine. 11.1,4-Bis-[2-(2-sulfoethyl)-pyridinium-(1)-methyl]-benzene. 12.1,2-bis-[2-(2-sulfoethyl)-pyridinium-(1)-methyl]-benzene. 13.1,3-bis-[2-(2-sulfoethyl)-pyridinium-(1)-methyl]-benzene. 14.1,4-bis-[4-(2-sulfoethyl)-pyridinium-(1)-methyl]-benzene. 15.2-[N-methallyl-pyridyl-(2)]-ethanesulfonic acid betaine. 16.2-[N-methallyl-pyridyl-(4)]-ethanesulfonic acid betaine.